Re: c compilation - gcc vs visual c

On May 10, 11:41 am, jacob navia <ja...@[EMAIL PROTECTED]
> wrote:
> Chris H wrote:
> > In message <g02blv$63...@[EMAIL PROTECTED]
>, jacob navia <ja...@[EMAIL PROTECTED]
>
writes
>
> >> It is not surprising that gcc is slower than Microsoft since the
> >> people behind each project have vastly different objectives and
> >> budgets to implement them.
>
> >> Gcc is running in many platforms and architectures.
> >> Microsoft is running in one platform exclusively.
>
> > So  Gcc is not likely to be good on any platform as the people who
> > develop for other platforms will specialise in that and beat GCC?
>
> This is very likely indeed. A specialized compiler for a given platform
> has less problems and can take advantage of many particular
> optimizations that a more general purpose compiler can't use.
>
>
>
> >> Gcc implements standards like C99
> > CRAP
>
> > GCC implements GNU-c and adds extensions for SOME parts of C99
>
> Apparently you can't just say
>
> "I disagree". No. You have to yell
>
> CRAP!!!
>
> Obviously you are right with "Some parts of C99" but those "some parts"
> are almost 99% of the job...
>
> >> (module small problems), Microsoft
> >> implements only Microsoft  environments (.net, etc). Microsoft is
> >> still at C89 level.
>
> > Microsoft along with every other compiler INCLUDING GCC is at C95 
with
> > SOME parts of C99 implemented.
>
> I disagree. Microsoft has done no effort at all to implemnt C99. The
only
> parts they did was // comments and accepting "long long". I am not aware
> of any other parts of C99 that they implement.
>
> > GCC is no more C99 than any other compiler.
>
> It is more advanced in its implementation of C99 than lcc-win.
>
> --
> jacob navia
> jacob at jacob point remcomp point fr
> logiciels/informatiquehttp://www.cs.virginia.edu/~lcc-win32

guys:
i have zeroed in and created a simple test program. This progrma just
has floating point addition and integer addition. it does 20 loops x
1million times. in relase version of visual c it takes 0 time. gcc O3
takes 6 secs in my machine.

this cannot be rocket science; there seems to some fundamental
deficiency in gcc. i will treat this as a bug. This should have
serious implications for linux platforms

here is the code; test it for yourself

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

static double loop (long times)
{
  long i=0;
  double a=0;

  for (i=1; i<times; i++)
    {
      double x1 = i-1;
      double x2 = i;
      double y = 0;
      long n=0;

      y = x1+x2;
      n = i+ i -1;

      y=x1*x2*y;

      a=y;
    }

  return a;

}

int main (int argc, char **argv)
{
  unsigned long times = 0;
  long i=0;
  time_t t=0;
  time_t t1=0;
  double dt=0;
  long lcnt=20;
  double a=0;

  times = (long) (1e9);

  /*
  if(argc > 1)
    {
      times = atoi (argv[1]);

      times *= 1e6;
    }

  if(argc > 2)
    lcnt = atoi (argv[2]);

  if(lcnt < 20)
    lcnt = 20;
  */
  time (&t);

  for (i=0; i<20; i++)
    {
      a = loop (times);
      /* you need this for visual c show any elapsed time
      printf ("\n %lg \n", a);
      */
    }





  time (&t1);

  dt = difftime (t1, t);

  printf ("\n times=%ld loops=%ld dtime = %lg \n", times, lcnt, dt);



  exit (0);
}